Calculating the difference between different rows with a common subject

Hi  

I have been attempting to get your solution to work and it does, to some extent , however when I look at the results it produces they are wrong however when giving you example data i did not incorporate other factors in and i think this is causing an issues.

Please let me give some data that reflects my data source better and see if it makes sense and you could get this to work(I will only use one student as an example and I will include the steps you have alreadty explained to me. I did adapt some of the formula to work with my data a bit better):

The data continues in a very similar pattern for all years with different names and some other changes.

from the example data in the tabel you would expect the autumn variable difference to be -1 as the calculation would do 2 (actual grade) - 3 (target grade) to give them -1 to show they are below target.

however after following your steps but tweaking them to try and fit my datat better I gte the answer of -3 which I am confused on how it would have gotten this answer.

Any help is really appreciated, I feel like it is so close to being resolved.

Thanking you so much in advance,

Luke,

(I have also attached a picture of the data to help with understanding)

Thanks again.